11 million years ago, Mars was a frigid, dry, dead world, just like it is now. Something slammed into the unfortunate planet, sending debris into space. A piece of that debris made it to Earth, found its way into a drawer at Purdue University, and then was subsequently forgotten about.<\/p>\n
Until 1931, when scientists studied and realized it came directly from Mars. What has it told them about the red planet?<\/p>\n
<\/p>\n 11 million years ago, the Himalayas were rising on a warmer, more humid Earth. Early ape species made their home in an Africa covered by tropical forests. Diverse mammal species roamed the continents. <\/p>\n At the same time, on Mars, the frigid wind blew across a desiccated, forlorn world. The planet\u2019s thin atmosphere is a weak barrier to meteorites, and the planet\u2019s cratered surface bears witness to its nakedness. Some impacts were powerful enough to launch debris into space beyond the planet\u2019s gravitational pull. The meteorite in the drawer is one such piece of debris. <\/p>\n \u201cMany meteoroids are produced by impacts on Mars and other planetary bodies, but only a handful will eventually fall to Earth.\u201d<\/p>\n Marissa Tremblay, Purdue University<\/cite><\/p><\/blockquote>\n<\/figure>\n The meteorite was long forgotten in its storage place until 1931. Scientists identified it as a piece of Mars, and now new research is uncovering clues about Mars\u2019 past hidden in the 800-gram piece of rock. <\/p>\n 11 million years ago is not a long time in geological and planetary terms, and the number fits neatly into most people\u2019s imaginations. But rock has deep temporal roots, and the meteorite that reached Earth is an igneous rock that dates back 1.4 billion years. That much time is more difficult to understand, but science is at its best when it opens human minds to a more fulsome understanding of nature. <\/p>\n The meteorite, named \u201cLafayette\u201d after the city in Indiana that\u2019s home to Purdue University, is the subject of new research published in Geochemical Perspectives Letters. It\u2019s titled \u201cDating recent aqueous activity on Mars,\u201d and the lead author is Marissa Tremblay. Tremblay is an assistant professor with the Department of Earth, Atmospheric, and Planetary Sciences (EAPS) at Purdue University. <\/p>\n There\u2019s ample evidence that some minerals on Mars formed in the presence of water. Though Lafayette itself is an igneous rock 1.4 billion years old, some of the minerals it contains are younger. <\/p>\n \u201cDating these minerals can therefore tell us when there was liquid water at or near the surface of Mars in the planet\u2019s geologic past,\u201d Tremblay said. \u201cWe dated these minerals in the Martian meteorite Lafayette and found that they formed 742 million years ago. We do not think there was abundant liquid water on the surface of Mars at this time. Instead, we think the water came from the melting of nearby subsurface ice called permafrost, and that the permafrost melting was caused by magmatic activity that still occurs periodically on Mars to the present day.\u201d<\/p>\n Lafayette is one of the Nakhlite meteorites, an igneous rock that formed from basaltic lava around 1.4 billion years ago. Scientists think these rocks formed in one of Mars\u2019 large volcanic regions: Elysium, Syrtis Major Planum, or the largest one, Tharsis, which is home to the three shield volcanoes, Tharsis Montes. <\/p>\n Ancient rocks and their embedded minerals contain information about Mars\u2019 ancient past. The history of Mars\u2019 hydrological cycle is a key objective in our ongoing study of Mars. This research is focused on a particular mineral in Lafayette called iddingsite. It forms when basalt is weathered in the presence of water. <\/p>\n The difficulty with meteorites and the clues they contain about ancient Mars is that they\u2019ve been exposed to and potentially altered by the heat of the initial impact and the heat of entry into Earth\u2019s atmosphere. The chemical signals inherent in rock can become muddied. But Lafayette is different. It\u2019s clear that it was blasted off of Mars 11 million years ago. <\/p>\n \u201cWe know this because once it was ejected from Mars, the meteorite experienced bombardment by cosmic ray particles in outer space that caused certain isotopes to be produced in Lafayette,\u201d Tremblay says. \u201cMany meteoroids are produced by impacts on Mars and other planetary bodies, but only a handful will eventually fall to Earth.\u201d<\/p>\n \u201cThe age could have been affected by the impact that ejected the Lafayette Meteorite from Mars, the heating Lafayette experienced during the 11 million years it was floating out in space, or the heating Lafayette experienced when it fell to Earth and burned up a little bit in Earth\u2019s atmosphere,\u201d Tremblay said. \u201cBut we were able to demonstrate that none of these things affected the age of aqueous alteration in Lafayette.\u201d<\/p>\n Study co-author Ryan Ickert is a senior research scientist in Purdue\u2019s EAPS. Ickert uses heavy radioactive and stable isotopes to study geological processes over time. He showed how isotope data used to date water-rock interactions on Mars were problematic and that the data had likely been polluted by other processes. According to Ickert, he and his colleagues got it right this time. <\/p>\n \u201cThis meteorite uniquely has evidence that it has reacted with water. The exact date of this was controversial, and our publication dates when water was present,\u201d he says.<\/p>\n The researchers used a novel technique involving the isotopes Argon 40 and Argon 39 to date Lafayette\u2019s exposure to water and its formation of Iddingsite. That showed them that the exposure occurred 742 million years ago. Their explanation is that magmatic activity melted subsurface ice, and the water subsequently found its way into cracks in the igneous rock, altering some of the olivine into Iddingsite. <\/p>\n All this from a meteorite that was lost in a drawer. <\/p>\n The Solar System is a puzzle. It\u2019s an artifact of Nature\u2019s ordered complexity, but at the same time, it\u2019s shaped by Nature\u2019s steadfast chaos. Each molecule, each tiny piece of rock, including the Lafayette meteorite, is a part of it. Each piece holds a clue to the puzzle. <\/p>\n \u201cWe can identify meteorites by studying what minerals are present in them and the relationships between these minerals inside the meteorite,\u201d said Tremblay. \u201cMeteorites are often denser than Earth rocks, contain metal, and are magnetic. We can also look for things like a fusion crust that forms during entry into Earth\u2019s atmosphere. Finally, we can use the chemistry of meteorites (specifically their oxygen isotope composition) to fingerprint which planetary body they came from or which type of meteorite it belongs to.\u201d<\/p>\n Dating these rocks, these pieces of the puzzle, is difficult. However, this research has made progress by developing a novel way to date minerals in the Lafayette meteorite. <\/p>\n \u201cWe have demonstrated a robust way to date alteration minerals in meteorites that can be applied to other meteorites and planetary bodies to understand when liquid water might have been present,\u201d Tremblay concluded.<\/p>\n\n
![\"A](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2016\/03\/tharsis_-_valles_marineris_mola_shaded_colorized_zoom_32-1200x800-1024x683.jpg\")
![\"This](\"https:\/\/www.universetoday.com\/wp-content\/uploads\/2024\/11\/GPL2443_Fig1_790.jpg\")
Like this:<\/h3>\n